1. Field of the Invention
This invention relates to digital data processing, storing and signal translating devices utilizing cylindrical magnetic domains (commonly called magnetic bubbles) in a uniaxially anisotropic magnetic medium such as a single orthoferrite crystal platelet. The present invention relates particularly to novel conductor patterns whereby the number of terminals and address planes required in prior bubble memories may be reduced. Additionally, this conductor pattern is utilized in a novel integrated correlator-memory to perform digital logic functions as well as nonvolatile bit storage with nondestructive readout on a single crystalline platelet using only two planar conductor arrays without crossovers.
2. Prior Art
Digital processing, storing and translating devices comprised of conductor arrays in magnetic coacting relationship with a uniaxial anisotropic crystalline platelet are well known. For example, several different serial shift register devices are described in the June 1971 issue of the magazine Scientific American in an article entitled "Magnetic Bubbles" written by A. H. Brobeck and H. E. D. Scovil. A rudimentary orthogonal array is described in U.S. Pat. No. 3,513,452, issued to Brobeck et. al, on May 19, 1970.
Improvements in the art of digital memories using magnetic bubbles were disclosed in my U.S. Pat. No. 3,806,899 entitled "Magneto Resistive Read-Out for Domain Addressing Interrogator," wherein conductor arrays defined two continuous domain retaining regions at each bit. In that patent, only one crystalline platelet was necessary when an optical readout means was employed. However, when magnetoresistive or other interrogation means were employed, independent control of magnetic bias on two platelets in close proximity as well as exact superposition and optical registration of the two platelets was required. Furthermore, light passing through the required two platelets in series caused twice the attenuation, thereby reducing the signal-to-noise ratio by one-half.
In my U.S. Pat. No. 3,806,903 entitled "Magneto-Optical Devices," there is disclosed a conductor array for a bubble device utilizable as a subtractive comparator or a random access memory. This device also had dual domain retaining regions at each bit location. However, the comparator function and the memory function could not be done simultaneously on a single platelet. Thus, if both functions were desired, two crystalline platelets were required with the disadvantages previously mentioned.
The devices disclosed in these two prior patents provided for various means of sensing the location of a bubble at one of two possible positions at each bit location in a single crystal platelet and disclosed a particular drive conductor configuration uniquely suited for this purpose. These devices contemplated use of separate interrogating or readout means such as a second crystal platelet positioned adjacent to the first. In my U.S. Pat. No. 3,878,542 entitled "Movable Magnetic Domain Random Access Three-Dimensional Memory Array," I disclosed an improved conductor array pattern which facilitated moving a single readout bubble between any one of three bit positions at a single bit location to permit both storage and readout functions from a single platelet. However, that device when utilizing a single platelet related only to memory storage and interrogation functions. No parallel correlation processing was possible as in the correlator-type array disclosed herein. If a correlation processing function was desired, two crystalline platelets were still required. Even in a pure storage and interrogation embodiment, each address coordinate required at least two conductors, one defining two contiguous domain retaining regions and the other defining a third contiguous domain retaining region.
Finally, some of the prior art conductor patterns have had sharp corners which formed spurious domain retaining regions thereby allowing bubbles to occasionally be captured at these sites in an uncontrolled manner. This limited the bit size of such memories.
Consequently, it is the general object of the present invention to provide an improved conductor array pattern for magnetic bubble devices. More specifically, it is an object of the present invention to provide a conductor array for bubble memories which decreases the number of terminals required per bit column and row. Another object of the present invention is to provide a bubble correlator-memory within the memory and correlator functions are integrated on a single crystalline platelet. Still another object of the present invention is to provide a correlator-memory which can stimultaneously store data in an updatable nonvolatile random access memory with non-destructive readout; provide sequential or parallel interrogation; and perform an "exclusive nor" logic function by mutual repulsion of juxtaposed wavering bubble domains in interrogation lines. Yet another object of the present invention is to provide a multiple bit conductor array pattern for bubble memories which eliminates the capture of bubbles at spurious locations. Still another object of the present invention is to provide a means of performing bit-addressable bipolar correlation of digital information at high speed with low power consumption.